1. Field of the Invention
The present invention relates to a jet-propulsion small watercraft such as a personal watercraft (PWC) which ejects water rearward and planes on a water surface as the resulting reaction. More particularly, the present invention relates both to a small watercraft comprising an actuator for driving a steering throttle drive means configured to open a propulsion throttle valve a predetermined angle under a predetermined condition, thereby maintaining a steering capability, when the throttle valve is operated to be closed, and to the actuator.
2. Description of the Related Art
In recent years, jet-propulsion personal watercraft, which are one type of jet-propulsion small watercraft, have been widely used in leisure, sport, rescue activities, and the like. The jet-propulsion personal watercraft is configured to have a water jet pump that pressurizes and accelerates water sucked from a water intake generally provided on a bottom hull surface and ejects it rearward from an outlet port. Thereby, the personal watercraft is propelled.
In the jet-propulsion personal watercraft, a steering nozzle provided behind the outlet port of the water jet pump is swung either to the right or to the left, to change the ejection direction of the water to the right or to the left, thereby turning the watercraft to the right or to the left.
In the jet-propulsion personal watercraft, when the throttle valve is moved to a substantially fully closed position and the water ejected from the water jet pump is thereby reduced, the propulsion force necessary for turning (steering) the watercraft is correspondingly reduced, and the steering capability of the watercraft is therefore reduced until the throttle valve is re-opened.
To solve the above problem with a mechanical structure, the applicant disclosed a jet-propulsion watercraft comprising a steering component for a steering system which is capable of maintaining a steering capability even when the throttle valve is moved to the substantially fully closed position and the water ejected from the water jet pump is thereby reduced (Japanese Laid-Open Patent Application Publication No. Hei. 2001-191992).
In the jet-propulsion watercraft, the number of components is large, so that its structure becomes complex and its weight increases. In view of this, the applicant also disclosed a jet-propulsion watercraft that has a simple structure without an increase in its weight (Japanese Laid-Open Patent Application Publication No. Hei. 2002-303170).